1. Field of the Invention
This invention relates to a process using mixed basic metal oxide catalysts for production of higher hydrocarbons by oxidative coupling of aliphatic and alicyclic hydrocarbon compounds with aliphatic and alicyclic substituted aromatic hydrocarbon compounds to form a longer substituent hydrocarbon on the aromatic ring. Reaction of methane with toluene and oxygen in the presence of a mixed basic metal oxide catalyst according to this invention results in high conversion to form styrene.
2. Description of the Prior Art
Methane is currently available in large quantities from natural gas, anaerobic digestion of organic material, and chemical processing sources. However, use of methane as a chemical feedstock has been limited due to its high stability. It has been highly desirable to develop a catalyst for such reactions to enable operation under milder conditions with greater control over thermodynamic and kinetic processes as well as provide product selectivity and high reaction rate.
Oxidative coupling of methane to form higher hydrocarbons has been shown to be effected over a number of metal oxides, but yields of desired products have been low, as discussed by Keller, G. E. and M. M. Bhasin, J. of Catalysis 73, 9-19 (1982). Sodium and lead on alumina has been found to catalyze the formation of ethane and ethylene from methane, as disclosed in Hinsen, W. and M. Baerns, Chem.-Ztg., 107, 223-226 (1983) and Hinsen, W., W. Bytyn and M. Baerns, Proc. 8th Int. Congr. Catal., Berlin, III 581-592 (1984). Several U.S. patents teach a series of supported metal oxides which while effective for the conversion of methane to ethane and ethylene, are based on reducible metal oxides and used in a stoichiometric fashion by alternately exposing them to an oxidizing atmosphere and then to methane in the absence of oxygen. U.S. Pat. Nos. 4,443,644; 4,443,645; 4,443,646; 4,443,647; 4,443,648; 4,443,649; 4,444,984, 4,499,322; 4,499,323; and 4,499,324; and 4,523,049.
Later work has demonstrated that magnesium oxide and calcium oxide, when promoted with alkali metal salts, are active for oxidative coupling of methane to ethane and ethylene in the presence of oxygen. See Kimble, James B. and John H. Kolts, "Oxidative Coupling of Methane to Higher Hydrocarbons", Energy Progress, Vol. 6, p. 227 (1986); Driscoll, D. J., W. M. Martir, J. Wang and J. H. Lunsford, J. Am. Chem. Soc. 107, 58-63 (1985); and Ito, T., J. Wang, C. Lin and J. H. Lunsford, J. Am. Chem. Soc. 107, 5062-64 (1985). These later catalysts have the advantage of operating continuously, not requiring regeneration or pretreatment.
Borates and boron compounds have been used in partial oxidation of hydrocarbons, such as boric acid to oxidize long chain normal paraffins in the liquid phase (Illingworth, G. F. and G. W. Lester, ACS Petroleum Division Preprints, 12, No. 3, 161 (1967)) and oxidation of n-dodecane in the liquid phase to the corresponding alcohol (Lee, K. W., M. J. Choi, S. B. Kim and C. S. Choi, Ind. Eng. Chem. Res. 26, 1951 (1987)). Boric acid has been used by coating reactor walls in the combustion of methane to eliminate free radical destruction at temperatures of less than 513.degree. C. (Kegeyan, E. M., I. S. Vardanyan and A. B. Nalbandyan, Kinetics and Catalysis 17, No. 4,749-754 and No. 4,755-759 (1976))
A review of styrene synthesis processes is given in Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, Vol. 21, Styrene, pgs. 770-801.
Vapor phase alkylation of aromatic hydrocarbons in the presence of a crystalline aluminosilicate zeolite catalyst is taught by U.S. Pat. Nos. 4,107,224 and 3,751,506.
A number of publications describe oxidative methylation of toluene performed in Russia: Chemical Abstracts 97:127153K (1982) teaches non-catalytic methylation of toluene depended mostly on pressure and PhMe/0/CH.sub.4 molar ratio; Chemical Abstracts 99:70137t (I983) teaches oxidative methylation of toluene using a Ni-V oxide or V oxide catalyst; Chemical Abstracts 101:74734t (1984) teaches oxidative methylation of toluene in presence of 0 (max. 15 percent in reaction mixture) results in products including styrene; Chemical Abstracts 101:38205 n (1984) teaches simultaneous production of styrene, ethylbenzene, benzene, and phenols by reaction of toluene with C.sub.1-4 alkanes in the presence of 0 and Fe.sub.2 O.sub.3 or TiO.sub.2 at 600.degree.-800.degree.. Productivity increased at higher pressure in presence of H.sub.2 O.sub.2 and/or (Me.sub.3 C).sub.2 O.sub.2 and U.S. Pat. No. 3,830,853 teaches reaction of toluene with a lower paraffin hydrocarbon in the presence of oxygen at 600.degree.-900.degree. C. and space velocity of 2000-10000 hour.sup.-1.